Polyfluorohydrocarbon resin compositions as cushion and cover compositions for v-belts

ABSTRACT

V-BELTS CONTAINING THE CUSHION COMPOSITIONS AND/OR ELASTOMERIC IMPREGNATED FABRIC ENVELOPES WHICH CONTAIN POLYFLUOROHYDROCARBON RESINS WHICH INCREASE THE RESISTANCE TO FAILURE DUE TO FLEXING OF SAID V-BELTS.

Uniw

f 3,661,823.,;, I V POLYFLUOROHYDROCARBON RESIN COMPOSI TIONS ,AS. CUSHION ANILL COVER ,CQMPOSI- TIONS FOR V-BELTS f Olson, and John'C. Wolfe,

No. 38,643 V Int. Cl. C08d 13/00 US. Cl. 26017.4 BB. a

Claims ABSTRACT OF DISCLOSURE V-belts containing the cushion compositions and/ or elastomeric impregnated fabric envelopes which contain polyfluorohydrocarbon resins which increase the resistance to failure due to flexing of said V-belts.

This application is a division of application S.N. 703,248, filed Feb. 6, 1968, and now U.S. Pat. 3,541,872.

This invention relates to cushion stocks for V-belts, elastomeric impregnated fabric envelopes for V-belts, V- belts containing said cushion stocks and fabric envelopes, and a process for improvingthe resistance to failure due to flexing of said Y-belts. 4 a

,In the art of power transmission V-belts characterized by a cross section in the form of a trapezoid or truncated V which wedgingly engages the similarly shaped peripheral groove of a V pulley are. employed in an ever increasing number of applications'A primary reason for this popularity is the improved load carrying and power transmitting capability afforded by the forced contact between the sides of the belt and the sides of the pulley groove which resist slippage of the belt in the pulley. These well known belts are normally characterized by such basic elements as a tension member composed of a rubber insulated cord layer, and a compression (cushion) section. An example ofabelt of thistype .is described and illustrated (FIG. 3) in US. Pat. 3,051,212. Often the belt is covered by a rubberized fabric envelope which covers the entire surface of the belt. An example of such an envelope is discussed and shown in US. Pat. 3,260,126. In other instances no envelope is used, resulting in what is commonly known a a'molded or raw edge belt. As a result of the severe operating conditions to which V-belts are often subjected, the resistance of the belts to failure due to flexing has become increasingly important. In addition, where the cushion section of the belt is not covered by a rubberized fabric the surface of the cushion after vulcanization can possess imperfections which not only detract from the appearance of the cushion section, but in addition, provide sites for flex cracking and other forms of deterioration to occur. It is therefore desriable to improve the performance and appearance of V-belts. It is desirable that the resistance to failure due' to flexing be improved. Such failure can take the form of dela'mination of the elements of the belt and cord separation. Increased abrar sion resistance is also desirablelt isalso desirable to'provide cushiousections with less surface imperfections in order to improve theappearance of the surface of the cushion stock andalso, to aid in preventing flexv cracking and other forms of deterioration;

It is an object of the present-invention to provide V- belts with improved resistance to failure due to flexing and improved abrasion resistance, cushion stocks and elastomeric impregnated fabric envelopes (fabric covers) 3,661,823 Patented Mt y ICC resistance'to failure due to flexing and aid in providing improved abrasion resistance, and a process for improving the resistance to failure due to flexing andto improve the. abrasion resistance of V-belts. j. r

Some of the objects of thevpresent invention are ac-. complished by blending a carbon black loaded composition comprising (A) 100 parts by weight of at least one elastomeric compound comprising (1) from about 50 to 100 parts by weight per 100 parts by weight of the elastomeric compound of polychloroprene and (2) from 0 to about 50 parts by weight per 100 parts by weight of the elastomeric compound of at least one rubbery diene polymer, (B) from about 0 to about 75 parts by weight per 100 parts by weight of the elastomeric compound of at least one flexible filamentary material and (C) from about 0.5 to about 20.0 parts by weight per 100 parts by weight of the elastomeric compound of at least one polyfluorohydrocarbon resin and then building a V-belt using the above composition to form the cushion portion of the belt and vulcanizing said V-belt. Some objects are accomplished by impregnating fabric with the above composition to form fabric envelopes for V-belts. Other objects will appear subsequently herein.

Preefrably the elastomeric compound consists essentially of polychloroprene, i.e., the rubbery polymer of 2-chlorobutadiene-l,3. This material is designated as ASTM D l418-56T at (C).

Rubbery diene polymers which may be used in combination with the polychloroprene include natural rubber, such as crepe rubber, and synthetic rubbers such as homopolymers of a conjugated 1,3-diene such as isoprene and butadiene, and in particular, polyisoprenes and polybutadienes having essentially all of their repeating units combined in a vis-1,4 structure; copolymers of a conjugated 1,3-diene such as isoprene and butadiene with up to 50 percent by Weight of at least one copolymerizable monomer such as styrene and acrylonitrile; and polymers of monoolefins containing unsaturation, i.e., carbon to carbon double bonds, such as terpolymers of ethylene, propylene and a nonconjugated diene.

The flexible filamentary material to be used in the practice of the present invention may be any flexible fiber of a shortened length which is generally used to increase the stitfness and hardness of cushion stocks. Such usage of fibers is noted in US. Pat. 3,051,212, column 4, lines 67 and 68. Well known fibers such as cotton linters and chopped or ground polyamides, such as nylon, regenerated cellulose such as rayon; and polyester fibers are exemplary of the types of the materials that may be used as flexible filamentary materials. The materials should be of such size that they can be dispersed uniformly throughout the cushion stock, and of such size to provide an increase in stiffness and hardness of the cushion stocks. Preferably from about 5 to about 30 parts by weight of the flexible filamentary material are used.

Polyfluorohydrocarbon resins, which have polymer lubricating properties, which may be used in the practice of the present invention are essentially completely fluorinated polymers such as polytetrafluoroethylene and essentially completely fluorinated ethylene propylene copolymers such as those made by.copolymerizing hexafluoropropylene and tetrafluoroethylene. Preferably from about 1.0 part to about 5.0 parts of the polyfluorohydrocarbon resin are used per 100 parts by weight of the elastomeric compound. It,is preferred that the polymers be in powdered form to facilitate ease of incorporation into the which. will; aid ,in providing. said V-belts withimproved elastomers with conventional mixing equipment.

The method of combining the components of the cushion stock is not normally critical. Theelastomeric compound, flexible filamentary material and polyfluorohydrocarbon resin may be mixed bysuch methods as;Banbury iinxmg afide ii mill The components may be mixed in-qany order; in inerements anddn-any combina vulcanizq the cushion stock: When. the ela'stomericjcolm pound; :of Lthe'. cushion stock 7 consists. essentially of poly; chloroprene, materialsrsuch -'aszinc-oxide may .be used to vulcanize the cushion stock. Wherediene polymers are usedas a portion of the elastomeric-compound it .is preferred that some sulfur vulcanization system beused.

Anyconventionalcarbon black may be used to load the cushionrstock. The level of; black shouldnormally-be from about 10 to about 90 parts by weight per 100 parts by weight of the elastomeric compound. A range of from about 20 to about 40 parts by weight is preferred.

The cushion stock composition may also be used to impregnate fabric to form fabric envelopes for V-belts, with the qualification that it preferably contains essentially no fiber loading. An example of a fabric envelope for a V- belt is shown in FIG. 6 and discussed at column 5, lines 26 to 28 of US. 3,260,126. The fabric may be any conventional V-belt fabric, e. g., cotton, rayon, nylon and polyesters. The fabric may be impregnated in any conventional manner, for example by swelling the elastomer in an organic solvent to form a dough-like composition, spreading the dough-like composition on the fabric and driving off the organic solvent. Said envelopes improve the resistance to failure due to flexing of V-belts.

The following examples contain illustrations of the practice of the present invention and are not intended to limit the present invention.

EXAMPLE 1 Parts by Components: weight Nonproductive polychloroprene stock 64.50 Scrap 25.00 Zinc oxide 3.50 Chopped cotton, rayon and nylon fibers 7.00

The cushion portion of belts E through H was prepared by milling together the following formulation.

Parts by Components: Weight Nonproductive polychloroprene stock 45.80 Scrap 50.00 Zinc oxide 3.53 Polytetrafluoroethylene 1 0.67

1 Teflon, TL: 115.

The nonproductive polychloroprene stock contained 100 parts by weight of polychloroprene as its sole elastomeric component, 20.0 parts of PEP carbon black, magnesium dioxide, processing oil, stearic acid, phenylbetanaphthylamine and phenylalphanaphthylamine.

The scrap was unvulcanized productive V-belt scrap whichhad been ground into fine particles. The scrap V: belts .were similar to belts A through I-I regarding :botb constructionaand composition. However, the cushion portion did. not contain polytetrafluoroethylene. The .insula tion portion of the V-belt scrap comprised approximately '20 percentby==weight of the'V-belt scrap. The'polyester cord comprised about percent by weight. The cushion portion comprised about 75 percent by weight. Theinsulation portion contained 100 parts by weight of polychloro- 3 that the cushion portion of beIts' E t' H contai prene-as.,its sole elastomeric component, 20.0. parts, of

FEFs black, 10.0 parts of cotton linters, reinforcing silica,

scope-of the present inventionitbeltsA to D).

magnesium oxide, process1ng oil, steanc acid, Zll'lC oxide,

a =polyethylene-waxqeleasing=agent-and-phenylalphanaphthylamine.

scrap had approximately the same composition as the cushr-nxa i I 1-5 percent by weight ofchopped teftrafiuoroethylene' and the cushion portions of belts 'A to D contained no polytetrafluoroethylene. Bothsetsk contained a -tensile portion con iprisedI of polyeste' insulated by an elastomeric formulation simila sulation composition described earlier hereiin.

Cushion stocks for V-belts within the scope of, the pres; ent invention are alsosprepared. by mixing the following compounds on an open mill. 7

are interchangeable with c'd'tton'linters. Other essentially completely fluoronated polyfluorohydrocarbon' resins SllCh as essentially completely fluoronatedethylene propylene copolymer are also interchangeable-with polytetrafluoroethylene.

The belts of lExamplel were dynamically tested -;0 a pulley arrangement according .tO SAE procedureJ I (SAE Handbook, 1967, edition), at 13 horsepower the exception that thesrnall-pulley was 2 .5 inches in diam; eter. The time to first failure as indicatedby the first part ing of any of the elements of the belt from the rest ofthe belt was recorded. 1 1,1,:

Condition of-belt 'at failure. w

Belt: J A Components separated at-cordline; top

iabriccameofi. B- Top fabric came 01?, edge'cord'cameout sideofbelt. r C Top fabric came off, edgecordeameout .7 2,38

sideoibelt. 'fl D olslligon section delaminatedsirom rest of e Average E dge cord-broke outside of tion at cordline.

Average :4.

bel

' .As shown by the abovev data. the: belts possessingiacushionwithin. thezscope of the present invention (belts E to 1H) possesseda gresistancelto'failure due to; flexing which was superior 10.:theresistance of belts outside-the The surfaces of theg-cushion portions of belts A to also contained some surfaceimperfections,'- whereas the surface of the cushionmortions of belts. E. to-H contained noaPPreciable surface imperfections. 1

Thebelts testedin Example 3 did nOt-Possessa fabric envelope surroundingv the cushionelement. Tests,;how= ever, have beenrun with belts containing a cushion element surrounded by a fabic envelope. The cushion element contained polytetrafiuoroethylene. These belts also showed improved resistance to failure due to flexing. The use of polyfluorohydrocarbon resins also enhances the abrasion resistance of the cushion stocks.

EXAMPLE 4 Eight V-belts (I through P) were constructed in essentially the same fashion as the belts A to 1) described in Example 1 and vulcanized. The composition of the elements was similar to the composition of the elements of belts A to D. The construction of the belts ditfered in that each belt contained a fabric envelope (cotton/nylon blend) impregnated with a black loaded (50 parts by weight of black) productive polychloroprene stock. The fabric was impregnated by swelling the polychloroprene composition with an organic solvent to form a dough-like composition, spreading the dough-like composition on the fabric and driving off the solvent. The cushion stock of these eight belts did not contain fiber loading. Four belts (M to P) contained polytetrafiuoroethylene in the polychloroprene portion of the fabric envelope, also known as a fabric cover. The other four belts *(I through *1.) contained no polytetrafiuoroethylene in the fabric envelope. The belts were tested in a manner similar to that described in Example 3 using a 2.5 idler pulley, a tension of 140 pounds and 14 horsepower.

Time to failure (hours) Average 103 As shown by the above data, belts M through P of the present invention were superior in performance.

The use of polyfluorohydrocarbon resins also enhances the abrasion resistance of the fabric envelopes.

Belt:

Average While certain representative embodiments and details have been shown for the purpose of illustrating the invention it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

What we claim is:

1. An elastomeric composition comprising (A) 100 parts of at least one elastomeric compound having ((1) from about to 100 parts of polychloroprene and (2) from about 0 to about 50 parts of a different rubbery diene polymer; (B) from about 5 to about 30 parts of at least one flexible filamentary material; (C) from about 0.5 to about 20.0 parts of at least one polyfluorohydrocanbon resin selected from the group consisting of polytetrafiuoroethylene and essentially completely fiuoronated ethylene propylene copolymer resins; and (D) from about 10 to about parts of carbon black, said parts being by weight per parts of elastomeric compound.

2. A composition according to claim 1 wherein the elastomeric compound consists essentially of polychloroprene.

3. A composition according to claim 1 wherein the flexible filamentary material is selected from the group consisting of a polyamide, regenerated cellulose, polyester and cotton.

4. A composition according to claim 1 wherein the polyfluorohydrocarbon resin is polytetrafiuoroethylene.

5. A composition according to claim 3 wherein the amount of polyfluorohydrocarbon resin is from about 1.0 to about 5.0 parts.

References Cited UNITED STATES PATENTS 3,002,938 10/ 1961 Gagne 260890 X 3,011,221 12/1961 Howell 260890 X 3,223,676 12/ 1965 Rucker 260-890 X WILLIAM H. SHORT, Primary Examiner L. L. LEE, Assistant Examiner US. Cl. X.R. 

